During a typical installation of a window in a building, a rough opening is first prepared in a wall of the building for receiving the window. The rough opening is defined by two jambs that extend vertically from a head at the top of the rough opening to a sill at the bottom of the opening. A weather resistant barrier material, such as a thin sheet of waterproof paper or plastic can be disposed over the outer surface of the wall, and the barrier material is cut at the rough opening and folded into the opening. The barrier material forms a moisture barrier extending over the outer surface, but due to the cuts in the barrier material does not normally provide a waterproof barrier on the inner surfaces of the rough opening. In particular, the barrier typically includes openings or cuts at the intersection of the jambs with each of the head and sill.
Flashings are often installed across the head and/or the sill, which extend outward from the head and sill onto a portion of the outer surface of the wall and upward from the sill onto a portion of each jamb. The flashings, which are formed of a flexible sheet of material, are cut and bent to correspond to the jambs, the outer wall surface, and the head or sill. Typically, two cuts are made in each of the head and sill flashing, each cut extending from a respective corner of the head or sill and the jambs, through the portion of the flashing that is disposed on the outer surface of the wall. Other cuts may be necessary depending on the configuration of the rough opening and the window. For example, if the rough opening has a curved head that corresponds to a semi-circular top portion of the window, the head flashing may be cut a number of times so that the flashing can be sufficiently bent to fit the curvature of the head.
In some cases, water can leak into the opening around or through the window or door. The water can sometimes penetrate both the barrier material and the flashings, e.g., through the cuts that are made in the barrier material and the flashing during installation. If the water flows into the wall, i.e., between the inner and outer surfaces of the wall, the water can damage to the wall and the window or door.
Thus, there exists a need for a product for use in a window or other portal installation for preventing the flow of water to the rough opening in the wall and to the inside of the wall. The product should be compatible with conventional windows and other portals and installation methods. In particular, the product should be compatible with windows of other portals with nonlinear sides, such as windows or doors with rounded or otherwise curved top or bottom portions. Preferably, the product should be relatively easy to install and economical to manufacture.